Expositor's Bible Commentary Commentary 3 John 1:12

"Demetrius hath the witness of all [men], and of the truth itself: yea, we also bear witness: and thou knowest that our witness is true." — 3 John 1:12 (ASV)

The elder now commends Demetrius, of whom we know no more than what is said of him here. For some reason John felt it important for Gaius to know and trust him. Apparently he was also one of John’s supporters. He may have been the bearer of this letter or a traveling missionary. John honors him with a threefold tribute: (1) He “is well spoken of by everyone.” (2) He is well spoken of “by the truth itself.” (3) The elder also “speaks well of him.” This strong backing of Demetrius leads us to think he had been given a special mission that required unusual trust, but one that the elder did not choose to describe here. What does John mean that “the truth” speaks well of Demetrius? It is the truth of the Gospel in Demetrius’s life that the elder is referring to. Like Gaius, Demetrius is “walking in the truth.” His life matches his confession. In Pauline terms, he manifests the fruit of the Spirit. In John’s terms, he lives the life of love. The clause “and you know that our testimony is true” reminds us of Jn 21:24.